It is known that, for the purpose of increasing a viscosity of a detergent composition to enhance a practical handling property of the detergent composition, or to stably disperse a water-insoluble substance, for example, a pearl brightening agent, an abrasive, etc, in the detergent composition, various types of thickening agents are mixed into the detergent composition.
As conventional main thickening methods, a method in which an inorganic salt, for example, sodium chloride is mixed into the detergent composition to agglomerate the micelles of the detergent with each other; a method in which a thickening polymeric agent is mixed into the detergent composition, and a method in which electrical mutual actions generated between the molecules of surfactant compounds in the detergent composition, are utilized for thickening the composition.
As a most common thickening method, it is known to use fatty acid alkanolamides as thickening agents. The fatty acid alkanolamides are surface-active agents exhibiting very excellent thickening (viscosity-increasing) effects and foam-stabilizing effects, particularly when used in combination with an anionic surface active agent. However, the fatty acid alkanolamides contain a nitrogen atom in the molecular structure thereof and, thus, in some surface active agent compositions, an undesired coloration of the composition unavoidably occurs with a lapse of time. Accordingly, development of a new type of thickening agent having a thickening property equal to or more than that of the fatty acid alkanolamides but not containing nitrogen atom in the molecular structure thereof has been demanded.
As a non-ionic surface active compound containing nitrogen atom and utilizable as a thickening agent, compounds having a very long polyoxyethylene chain segment, for example, polyethylene glycol distearate having a high addition degree of a polyoxyethylene segment, are known, and a method in which the above-mentioned compounds are used to exhibit the thickening effect thereof, is also known. This type of compounds has, however, a chemical structure similar to that of polymeric compounds and thus a problem such that when the compound is mixed, as a thickening agent, in a detergent composition, the compound causes the resultant mixture to exhibit an unpleasant slippery feel, occurs.
With respect to derivative compounds from hydroxyalkyl polyhydric alcohol ether, Japanese Unexamined Patent Publication No. 54-49322 (JP-54-49322-A) discloses that the derivative compound is used as a non-medical anti-bacterial and mildew-proofing agent. In this Japanese publication, it is reported that a hydroxyalkyl polyhydric alcohol ether compound having an excellent anti-bacterial and mildew-proofing property can be obtained when ethyleneglycol is used as a polyhydric alcohol.
Also, in a rust preventive lubricant agent for zinc-plated steel sheet disclosed in Japanese Unexamined Patent Publication No. 7-173486 (JP-7-173486-A), an additive for lubricant oils and a lubricant oil composition disclosed in Japanese Unexamined Patent Publication No. 2000-17283 (JP-2000-17283-A), hydroxyalkyl polyhydric alcohol ether compounds having a fluidity-enhancing effect and a rust preventive effect are employed. However, none of the above-mentioned prior art publications discloses that the hydroxyalkyl polyhydric alcohol ether compounds are mixed, as a thickening agent, into detergents. Namely, in the above-mentioned publications, the employment of the hydroxyalkyl polyhydric alcohol ether compounds for the purpose of cleaning or lavation is not disclosed.
With respect to the use as a detergent, Japanese Unexamined Patent Publication No. 01-67235 (JP-01-67235-A) discloses a method in which, in the preparation of an aqueous ionic surface active agent-containing detergent, hydroxyalkyl polyhydric alcohol ether compounds are mixed into water-soluble ionic surface active agents, is disclosed. In this prior method, the employed polyhydric alcohols include ethylene glycol, glycerol, erythritol, pentaerythritol, trimethylolpropane, sorbitol, cyclohexanetriol and inositol. Further, the publication reports that in consideration of the degree of increase in the viscosity of the mixture of the water-soluble ionic surface active agent with the polyhydric alcohol, glycerol and trimethylol propane are preferably employed as the polyhydric alcohols.
In fact, although hydroxydodecyl glycelylether produced from glycerol and 1,2-epoxydodecane can be used as a viscosity-modifier of the surface active agent composition, this compound has a problem such that the compound has a very high melting point and causes the resultant composition to exhibit a decreased stability at low temperature. Therefore, the compound has a low usability in practice.
Japanese unexamined Patent Publication No. 11-315043 (JP-11-315043-A) discloses a composition in which a hydroxyalkyl polyhydric alcohol ether compound prepared by using a solid acid catalyst is mixed into a detergent. The Japanese publication reports that, in the preparation of the ether compound, the polyhydric alcohol is preferably selected from polyhydroxy compounds, for example, glycerol, diglycerol, triglycerol, tetraglycerol, polyglycerol, glucose, methylglucoside, ethylglucoside, alkyl polyglucoside, sorbitol, mannitol, and pentaerythritol. The hydroxyalkyl polyhydric alcohol ether compounds produced from the above-mentioned polyhydroxy compounds exhibit an enhanced solubility in water. However, the compound is not always satisfactory in the thickening effect on the detergent, in comparison with that of the conventional fatty acid alkanolamide compounds.